1,720,995 research outputs found
Quantum energy momentum tensor and equal time correlations in a Reissner-Nordström black hole
Full text linkWe consider a Reissner-Nordström black hole formed by the collapse of a charged null shell. The renormalized expectation values of the energy-momentum tensor operator for a massless scalar field propagating in the two-dimensional section of this spacetime are given. We then analyze the across-the- horizon correlations of the related energy density operator for free-falling observers to reveal the correlations between the Hawking particles and their interior partners
The Unruh Vacuum and the “In-Vacuum” in Reissner-Nordström Spacetime †
Full text linkThe Unruh vacuum is widely used as a quantum state to describe black hole evaporation since, near the horizon, it reproduces the physical state of a quantum field, the so-called "in-vacuum", in the case where a black hole is formed by gravitational collapse. We examine the relation between these two quantum states in the background spacetime of a Reissner-Nordstrom black hole (both extremal and not), highlighting the similarities and striking differences
Black hole thermodynamics and backreaction
No full textNew and unexpected thermodynamical features of uncharged and non-rotating black holes are discussed starting from a backreaction-corrected temperature expression
Regular vacuum states for Schwarzschild black holes
No full textThe immersion of a Schwarschild black-hole space-time in a cosmological medium leads to a natural definition of a whole family of invacuum states characterized by finite expectation values of the two-dimensional stress-energy tensor at the horizons. © 1989 Società Italiana di Fisica
Five-dimensional quantum gravity and the residual length
No full textA five-dimensional Kaluza-Klein model is discussed. One derives, as a consequence of the quantum fluctuations of the geometry, the existence of a residual length in the four-dimensional space-time we perceive as physical. © 1986 The American Physical Society
Ramp-up of Hawking Radiation in Bose-Einstein-Condensate Analog Black Holes
Full text linkInspired by a recent experiment by Steinhauer and co-workers, we present a simple model which describes the formation of an acoustic black hole in a Bose-Einstein condensate, allowing an analytical computation of the evolution in time of the corresponding density-density correlator. We show the emergence of analog Hawking radiation out of a "quantum atmosphere"region significantly displaced from the horizon. This is quantitatively studied both at T=0 and even in the presence of an initial temperature T, as is always the case experimentally
The backreaction and the evolution of quantum black holes
No full textAn approach toward a self-consistent treatment, at a semiclassical level, of black hole evaporation is presented. The different backreaction effects of massless scalar and vector fields are discussed. On this basis a new evolution scheme for evaporating black holes is suggested in which the evaporation comes to an end before all mass is radiated away
Behaviour of a test field in a vacuum bubble space-time
No full textThe quantum behaviour of a scalar test field is described in a massive true vacuum bubble space-time. It is shown that, if we take into account the cosmological-medium contribution, the expectation value of the stress energy tensor of the test field is regular at every instant of the bubble evolution. © 1988 Società Italiana di Fisica
Switching off black hole evaporation?
No full textThe inclusion of the back-reaction in the Hawking effect leads to the result that, if vector boson fields predominate in nature, then black holes stop evaporating when their mass reaches a non-vanishing limiting value
Matter, quantum gravity, and adiabatic phase
No full textBased on the observation that particle masses are much smaller than the Planck mass, a framework for the matter-gravity system in which matter follows gravitation adiabatically is examined in a path-integral approach. It is found that the equations that the resulting gravitational wave function satisfies involve, in addition to the expectation value of the matter stress tensor, an adiabatically induced gauge field which can lead to interesting topological structures in superspace. Such a non-trivial geometric contribution modifies the semiclassical quantization condition and can change the conserved quantities associated with the symmetries of the system. © 1990 The American Physical Society
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